All-optical atomic clock could tell precise time

A team of researchers at the University of Colorado has developed an all-optical atomic clock that could be more precise than the current microwave atomic clocks. The work is published in Science.

"To call it the most accurate clock in the world would be incorrect at this point. It has the potential to be 1000 times more accurate than current atomic clocks, but that remains to be verified," said Scott Diddams of The National Institute of Standards and Technology.

The clock is based on the optical frequency of a single, cooled mercury ion linked to a laser oscillator.

"The clock's oscillator is one mercury ion which is held in a vacuum at cryogenic temperatures," said Diddams.

Atomic clocks derive their frequency from atomic transitions. In current atomic clocks the frequency is determined by transitions that are made in cesium atoms at microwave frequencies.

Optical transitions occur at much higher frequencies, providing a much finer division of time.

"Microwave clocks oscillate at 10bn oc/s and this oscillates at 1015 oc/s," said Diddams.

"Currently its applications are limited to scientific applications. This technology should be the basis of the next generation of atomic clocks, but it will be about 10 years before it is actually common."